Session 2 Lecture Notes

Question 1

What is an endotoxin?

Answer 1

A toxin that is part of the bacteria structure

Question 2

What is the best example of an endotoxin?

What does it contain on its outer membrane?

Answer 2

Gram Negative Bacteria

They contain lipopolysaccharide on their outer membrane which is highly toxic & can trigger an inflammatory response

Question 3

What colour does gram negative bacteria stain and why?

Answer 3

Stains pink/red with the counterstain due to lipopolysaccharide outer layer

Question 4

What are exotoxins?

Answer 4

Proteins secreted by bacteria that go out into surrounding tissue and fluid

Question 5

What is an enterotoxin?

Answer 5

An exotoxin that acts on the bowel

Question 6

What is a neurotoxin?

Answer 6

An exotoxin that acts on the nerves

Question 7

Name the 4 main micro-organisms that cause disease in order of small to large

Answer 7

1. Viruses
2. Bacteria
3. Fungi
4. Parasites

Question 8

What are prions?

Why can they cause problems for surgeons?

Answer 8

Proteins that can multiply and spread from person to person

- They cause disease and can withstand high temp and pressure (makes it hard when steralising equipment)

Question 9

Which microorganism can only exist in a host cell?

Answer 9

Viruses

They can use bacteria as their host cell

Question 10

What are the 2 layers of a virus membrane?

Answer 10

1. Envelope - a lipid bilayer

2. Protein coat - to protect genetic material

Question 11

What do the spikes on the surface of viruses do?

Answer 11

Allow the virus to attach to specific cell surfaces

Question 12

Can viruses have DNA or RNA and does this exist as single or double stand?

Answer 12

Can have RNA or DNA
It can exist as single or double strand
They can also be enveloped or non-enveloped
(RNA can also be helical or icosahedral shaped)

Question 13

What is the difference between positive and negative sense single stranded RNA viruses?

Answer 13

Positive sense single strand RNA viruses have to become negative in order to be read from and synthesise a 2nd strand
Negative sense single strand RNA viruses can be read from straight away and synthesise a 2nd strand

Question 14

Why do single stranded DNA and RNA viruses synthesise a 2nd strand immediately after infecting a host cell?

Answer 14

Because with just 1 strand they are subject to more mutations

Question 15

What is tissue trophism?

Answer 15

When viruses prefer certain cell lines

Question 16

What is a bacteriophage?

Answer 16

A virus that infects and replicates within a bacterium

Question 17

Do bacteria have a nuclear membrane?

Answer 17

No - their DNA is within the cytoplasm

Question 18

How many layers does a bacteria have before you reach the cytoplasm?

Answer 18

3:

1. Capsule - made of polysaccharides
2. Cell wall - an important target for antibiotics
3. Plasma membrane

Question 19

What part of the bacteria is an important target for antibiotics?

Answer 19

The cell wall

Question 20

Name three contents of bacterial cytoplasm

Answer 20

1. Ribosomes
2. Plasmids
3. Nucleoid (circular double stranded DNA)

Question 21

What are plasmids?

Answer 21

They are smaller circles of DNA that can replicable and transfer between bacteria
You may have 2 bacteria with same DNA but different plasmids

Question 22

Do all bacteria have the same capsules? (outer layer of polysaccharides)

Answer 22

No - different strains of bacteria have different capsules (it is a virulence factor)

Question 23

What are the 3 types of bacterial shape?

Answer 23

1. Coccus shaped (circular)
2. Spirillus (spiralled)
3. Bacillus (square/rod shaped)

Question 24

What are the two ways cocci bacteria can be arranged?

What are cocci bacteria?

Answer 24

1. Clusters
2. Chains
   Cocci shaped bacteria are round/circular

Question 25

What is the difference between gram negative and gram positive bacteria?

Answer 25

Gram positive - have peptidoglycan layer (outside plasma membrane) Gram negative - have smaller peptidoglycans but also have an "outer layer" made of lipopolysaccharides and protein (outside plasma membrane)

Question 26

What colour do gram negative and gram positive bacteria stain?

Answer 26

Positive - stain purple | Negative - counter stain stains red

Question 27

What are aerobes and anaerobes?

Answer 27

``` Aerobes = bacteria that can survive in presence of oxygen Anaerobes = bacteria that can survive in absence of oxygen ```

Question 28

What are spores?

Answer 28

Dormant form of bacteria

Question 29

Give an example of a cocci gram positive bacteria | State the shape and stain colour of this bacteria

Answer 29

Example: streptococcus pnuemoniae Cocci = round Gram positive = stain purple

Question 30

Give an example of a cocci gram negative bacteria | State the shape and stain colour of this bacteria

Answer 30

Example: Neisseria meningitidis Cocci = round Gram negative = counter stain red

Question 31

Give an example of a bacilli gram positive bacteria | State the shape and stain colour of this bacteria

Answer 31

Example: Bacillus cereus Bacilli = square/rod shape Gram positive = stain purple

Question 32

Give an example of a bacilli gram negative bacteria | State the shape and stain colour of this bacteria

Answer 32

Example: Salmonella typhi Bacilli = square/rod shaped Gram negative = counter stain red

Question 33

Why might it be difficult to create an anti-viral or anti-parasitic agent?

Answer 33

Because they are types of eukaryotic cells | There is a risk that damage to these could also cause damage to a human cell

Question 34

What are the 2 types of fungi called and are they single or multicellular?

Answer 34

1. Yeast - single called | 2. Mould - multicellular

Question 35

What are the 2 types of parasites called and are they single or multicellular?

Answer 35

1. Protozoa - single celled | 2. Helminths (worms) - multicellular

Question 36

What is the difference between calendar time and relative time?

Answer 36

Calendar time = when infections are more common at certain times of year Relative time = when infections have certain incubation periods (time until symptoms of infection are evident)

Question 37

There are 7 mechanisms of infection. Name as many as possible

Answer 37

1. Direct contact 2. Inoculation (sharps) 3. Haematogenous (blood) 4. Ingestion (food or drink) 5. Inhalation 6. Vector (insect) 7. Vertical transmission (from mother to child)

Question 38

What are the 3 steps you should follow to make a diagnosis?

Answer 38

1. History 2. Examination 3. Inflammation

Question 39

Give 2 examples of types of specific treatment and supportive treatment

Answer 39

``` Specific 1. Antimicrobials 2. Surgery Supportive 1. Symptom relief 2. Physical restoration eg oxygen ```